Methods and systems are provided for expediting emission control device heating. In one example, a method may include flowing air from an intake of an engine to one or more emission control devices via an air injection system while operating a turbocharger via an electric motor to maintain a desired airflow to the engine in response to an emission control device heating condition. In this way, fresh air is provided to the one or more emission control devices without degrading engine performance or increasing engine speed.

A method of controlling oxygen purge of a three-way catalyst may include: performing a fuel cut-off; determining whether a fuel cut-in condition is satisfied after the fuel cut-off; calculating an optimum valve overlap according to an intake amount, an engine rotation speed, and an ignition timing if the fuel cut-in condition is satisfied after the fuel cut-off; controlling a CVVD apparatus to be at the optimum valve overlap; and performing the oxygen purge at the optimum valve overlap.

An engine-driven working machine 1 is provided with: a diesel engine 10; a generator body 30 driven by the engine 10; an exhaust gas purification device 20 for purifying exhaust gas discharged from the engine 10; a VGT 13 for throttling intake air to the engine 10; and a reserve load 40 which can be connected between the generator body 30 and a load. The VGT 13 is throttled when removing deposition substances in the exhaust gas purification device 20, thereby increasing the temperature of exhaust gas from the engine 10, and the reserve load 40 is connected to the generator body 30 when throttling intake air in order to remove deposition substances in the exhaust gas purification device 20, thereby increasing the amount of intake air to the engine 10.

In a method for the regeneration of a particulate filter or of a four-way catalytic converter in an exhaust system of an internal combustion engine, an increase in the nitrogen oxide emissions during the regeneration of the particulate filter or of the four-way catalytic converter can be prevented or at least reduced. A particulate filter or a four-way catalytic converter is arranged in the exhaust system of an internal combustion engine. The fuel injection and the ignition are switched off in response to a request for the internal combustion engine to be turned off. Due to mass inertia, the internal combustion engine transitions from the switch-off rotational speed to a standstill whereby, during this phase, oxygen-rich air is conveyed into the exhaust passage. A partial regeneration of the filter or of the catalytic converter takes place with the oxygen contained in this fresh air, whereby the particulate mass discharged from the filter or the catalytic converter is determined by means of a computational model.

An engine control method for a vehicle may include a temperature securing determination step of determining, by a controller, whether an exhaust gas temperature before a turbine of a turbocharger is normally secured; a basic determination step of, when the exhaust gas temperature before the turbine is normally secured, obtaining, by the controller, a first compensation torque according to a current state of the vehicle from a first compensation torque map according to the exhaust gas temperature before the turbine, an engine operation mode, engine speed, and atmospheric pressure; and an engine control step of, when the exhaust gas temperature before the turbine is normally secured, determining, by the controller, a final compensation torque on the basis of the first compensation torque and controlling engine torque at a value which is obtained by subtracting the final compensation torque from engine full-load torque.

An exhaust purification system includes: an NOx reduction type catalyst; an MAF sensor; an SOx purge control unit that uses an air system control having an intake air amount feedback-controlled based on a target intake air amount and an injection system control for a target injection increase amount set based on the target intake air amount, and a fuel injection amount feedback-controlled based on the target injection increase amount; an SOx purge prohibition processing unit that prohibits an SOx purge control; and a warming mode control unit that open-loop controls an air system when the SOx purge control is prohibited, controls the fuel injection amount, and maintains the exhaust gas at a temperature. The SOx purge control unit executes the injection system control by switching the target intake air amount into an actual intake air amount when starting the SOx purge control after a warming mode control is ended.

An exhaust purification system including a NOx catalyst 32 provided in an exhaust passage of an internal combustion engine 10 and purifying NOx in exhaust; a MAF sensor 40 for acquiring an air flow-rate of the internal-combustion engine 10; a control unit 60, 70 that execute catalyst regeneration treatment of recovering a NOx purification ability of the NOx catalyst 32 by performing, in combination, air-based control of reducing air flow-rate of the internal-combustion engine 10 to a predetermined target air flow-rate and injection-based control of increasing a fuel injection amount, wherein, in a case of executing the catalyst regeneration treatment, the control unit 60, 70 starts with the air-based control and starts the injection-based control when the air flow-rate acquired by the MAF sensor 40 is reduced to the target air flow-rate.

Based on an exhaust gas temperature on an upstream side acquired by an upstream temperature acquisition device, in performing control of supplying an unburned fuel to an oxidation catalyst device in a case where the exhaust gas temperature on the upstream side is lower than a low temperature, a control device performs control of adjusting at least one of an injection timing of a cylinder injection valve and opening-closing timing of an exhaust valve at least one of before and after the supplying control; raising a temperature of the exhaust gas that substantially free of unburned fuel discharged from the exhaust valve to be higher than the low temperature; and warming the oxidation catalyst device until a predetermined warming period has passed.

A method of controlling oxygen purge of a three-way catalyst may include: performing a fuel cut-off; determining whether a fuel cut-in condition is satisfied after the fuel cut-off; calculating an optimum valve overlap according to an intake amount, an engine rotation speed, and an ignition timing if the fuel cut-in condition is satisfied after the fuel cut-off; controlling a CVVD apparatus to be at the optimum valve overlap; and performing the oxygen purge at the optimum valve overlap.

An engine control method for a vehicle may include a temperature securing determination step of determining, by a controller, whether an exhaust gas temperature before a turbine of a turbocharger is normally secured; a basic determination step of, when the exhaust gas temperature before the turbine is normally secured, obtaining, by the controller, a first compensation torque according to a current state of the vehicle from a first compensation torque map according to the exhaust gas temperature before the turbine, an engine operation mode, engine speed, and atmospheric pressure; and an engine control step of, when the exhaust gas temperature before the turbine is normally secured, determining, by the controller, a final compensation torque on the basis of the first compensation torque and controlling engine torque at a value which is obtained by subtracting the final compensation torque from engine full-load torque.